It is a trend in automobile industry to replace fuel vehicles by electric vehicles. However, safety of on-board battery packs has become one of problems hindering spreading of the electric vehicles.
Now, in order to reduce risks when an on-board battery pack is supplying electricity for an electric vehicle and satisfy function requirements of the electric vehicle, it is necessary to detect a current of the on-board battery pack and control a primary positive circuit and a primary negative circuit of the on-board battery pack.
Generally, the primary positive circuit and the primary negative circuit are specially designed external of a traditional battery management system, which cooperates with a current sensor or a current detecting unit to detect the current of the on-board battery pack, so the circuit structure is complex and the cost is high.